Exclusive dilepton production at forward rapidities in PbPb collisions

The dilepton production at forward rapidities in diffractive and exclusive processes present in ultraperipheral PbPb collisions at the LHC is investigated. Predictions for the $$e^+ e^-$$ e + e - , $$\mu ^+ \mu ^-$$ μ + μ - and $$\tau ^+ \tau ^-$$ τ + τ - cross sections are presented taking into account of realistic cuts that can be implemented by the LHCb Collaboration in a future experimental analysis. Our results indicate that the background associated with the diffractive production can be strongly suppressed and the exclusive processes can be cleanly separated. For the $$\tau ^+ \tau ^-$$ τ + τ - production, the semi and purely leptonic decay channels are considered. Our results indicate that a future experimental analysis of the dilepton production at the LHCb is feasible and can be useful to search for BSM physics.

Central exclusive diffractive production of two-pion continuum at hadron colliders

Calculations of central exclusive diffractive di-pion continuum production are presented in the Regge–eikonal approach. Data from ISR, STAR, CDF and CMS were analyzed and compared with the theoretical description. We also consider theoretical predictions for LHC, possible nuances and problems of calculations and prospects of investigations at present and future hadron colliders.

Tensor pomeron, vector odderon and diffractive production of meson and baryon pairs in proton-proton collisions

We review some selected results of the tensor-pomeron and vectorodderon model of soft high-energy proton-proton scattering and central exclusive production of meson and baryon pairs in proton-proton collisions. We discuss the theoretical aspects of this approach and consider the phenomenological implications in a variety of processes at high energies, comparing to existing experimental data. We consider the diffractive dipion and dikaon production including the continuum and the dominant scalar and tensor resonance contributions as well as the photoproduction processes. The theoretical results are compared with existing CDF experimental data and predictions for planned or current LHC experiments, ALICE, ATLAS, CMS, LHCb are presented.

Meson spectroscopy at VES and COMPASS

Diffractive production of π- π- π+ and π- π0 π0 final states is the subject of comprehensive studies performed recently by the VES and the COM-PASS experiments. COMPASS pioneered the application of novel methods of partial-wave analysis: mass-independent PWA inmultiple (m3π, t’)-cells, mass-dependent analysis of spin-density matrices performed simultaneously in all measured t’ bins, the analysis with freed shapes of π+ π- isobars. In addition, COMPASS observed a new narrow state: a1(1420). VES has world-leading data samples on π- π- π+ and π- π0 π0, that yield compatible results and show the potential for a detailed comparison of isospin relations between different decay channels, using the PWA methods with fixed and freed shapes of ππ isobars.